The present invention relates generally to a V-shaped plate of a type serving as a guide when mounted vertically on a rearwardly extending support of a towing vehicle in surrounding relation to a hitch ball to facilitate the hitching of a boat trailer or other trailer to the hitch ball and, more particularly, to improvements in the manner in which the V-shaped guide is assembled, preparatory to the hitching procedure, to the towing vehicle support so as to withstand the impact forces that are involved and yet retain the convenience of its being readily attachable and detachable to the towing vehicle support.